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Overdeepened structures occur in formerly and presently glaciated regions around the earth and are usually referred to as overdeepenings or tunnel valleys. The existence of such troughs has been known for more than a century, and they have been attributed to similar formation processes where subglacial meltwater plays a decisive role. This comparison highlights that (foreland) overdeepenings and tunnel valleys further occur in similar dimensions and share many characteristics such as gently sinuous shapes in plan view, undulating long profiles with terminal adverse slopes, and varying cross-sectional morphologies. The best explored examples of overdeepened structures are situated in and around the European Alps and in the central European lowlands. Especially in the vicinity of the Alps, some individual troughs are well explored, allowing for a reconstruction of their infill history, whereas only a few detailed studies, notably such involving long drill core records, have been presented from northern central Europe. We suggest that more such studies could significantly further our understanding of subglacial erosion processes and the regional glaciation histories and aim to promote more intense exchange and discussion between the respective scientific communities. Kurzfassung: In den ehemals und gegenwärtig vergletscherten Regionen der Erde finden sich übertiefte Beckenstrukturen, die üblicherweise als Übertiefungen oder Tunneltäler angesprochen werden. Die Existenz dieser Tröge ist seit mehr als einem Jahrhundert bekannt, und sie wurden ähnlichen Erosionsprozessen zugeschrieben, bei denen subglaziales Schmelzwasser eine entscheidende Rolle spielt. Mit diesem Vergleich möchten wir zeigen, dass (Vorland-)Übertiefungen und Tunneltäler in vergleichbaren Dimensionen auftreten, und eine Reihe weiterer gemeinsamer Merkmale aufweisen, zum Beispiel sanft gewundene Längsachsen, undulierende Profile mit Gegensteigungen am distalen Ende, und variable Formen im Querschnitt. Die bestuntersuchten Beispiele für übertiefte Becken befinden sich im europäischen Alpenraum, und in zentraleuropäischen Tiefländern. Vor allem im Alpenraum wurden einige übertiefte Strukturen detailliert untersucht, was eine Rekonstruktion ihrer Verfüllung erlaubt. Im Gegensatz dazu existieren nur wenige (bohrungsbasierte) Detailstudien im nördlichen Mitteleuropa. Wir betonen, dass solche Untersuchungen zu unserem Verständnis subglazialer Erosionsprozesse, aber auch regionaler Vergletscherungsgeschichten beitragen können, und möchten Austausch und Diskussion unter den entsprechenden wissenschaftlichen Lagern anregen. [ABSTRACT FROM AUTHOR]

The sedimentary infill of glacially overdeepened valleys (i.e., structures eroded below the fluvial base level) is an excellent but yet underexplored archive with regard to the age, extent, and nature of past glaciations. The ICDP project DOVE (Drilling Overdeepened Alpine Valleys) Phase 1 investigates a series of drill cores from glacially overdeepened troughs at several locations along the northern front of the Alps. All sites will be investigated with regard to several aspects of environmental dynamics during the Quaternary, with focus on the glaciation, vegetation, and landscape history. Geophysical methods (e.g., seismic surveys), for example, will explore the geometry of overdeepened structures to better understand the process of overdeepening. Sedimentological analyses combined with downhole logging, analysis of biological remains, and state-of-the-art geochronological methods, will enable us to reconstruct the erosion and sedimentation history of the overdeepened troughs. This approach is expected to yield significant novel data quantifying the extent and timing of Middle and Late Pleistocene glaciations of the Alps. In a first phase, two sites were drilled in late 2021 into filled overdeepenings below the paleolobe of the Rhine Glacier, and both recovered a trough filling composed of multiphase glacial sequences. Fully cored Hole 5068_1_C reached a depth of 165 m and recovered 10 m molasse bedrock at the base. This hole will be used together with two flush holes (5068_1_A, 5068_1_B) for further geophysical cross-well experiments. Site 5068_2 reached a depth of 255 m and bottomed out near the soft rock–bedrock contact. These two sites are complemented by three legacy drill sites that previously recovered filled overdeepenings below the more eastern Alpine Isar-Loisach, Salzach, and Traun paleoglacier lobes (5068_3, 5068_4, 5068_5). All analysis and interpretations of this DOVE Phase 1 will eventually lay the ground for an upcoming Phase 2 that will complete the pan-Alpine approach. This follow-up phase will investigate overdeepenings formerly occupied by paleoglacier lobes from the western and southern Alpine margins through drilling sites in France, Italy, and Slovenia. Available geological information and infrastructure make the Alps an ideal area to study overdeepened structures; however, the expected results of this study will not be restricted to the Alps. Such features are also known from other formerly glaciated mountain ranges, which are less studied than the Alps and more problematic with regards to drilling logistics. The results of this study will serve as textbook concepts to understand a full range of geological processes relevant to formerly glaciated areas all over our planet. [ABSTRACT FROM AUTHOR]

The glacial landscape of the Alps has fascinated generations of explorers, artists, mountaineers, and scientists with its diversity, including erosional features of all scales from high-mountain cirques to steep glacial valleys and large overdeepened basins. Using previous glacier modelling results and empirical inferences of bedrock erosion under modern glaciers, we compute a distribution of potential glacier erosion in the Alps over the last glacial cycle from 120 000 years ago to the present. Despite large uncertainties pertaining to the climate history of the Alps and unconstrained glacier erosion processes, the resulting modelled patterns of glacier erosion include persistent features. The cumulative imprint of the last glacial cycle shows a very strong localization of erosion potential with local maxima at the mouths of major Alpine valleys and some other upstream sections where glaciers are modelled to have flowed with the highest velocity. The potential erosion rates vary significantly through the glacial cycle but show paradoxically little relation to the total glacier volume. Phases of glacier advance and maximum extension see a localization of rapid potential erosion rates at low elevation, while glacier erosion at higher elevation is modelled to date from phases of less extensive glaciation. The modelled erosion rates peak during deglaciation phases, when frontal retreat results in steeper glacier surface slopes, implying that climatic conditions that result in rapid glacier erosion might be quite transient and specific. Our results depict the Alpine glacier erosion landscape as a time-transgressive patchwork, with different parts of the range corresponding to different glaciation stages and time periods. [ABSTRACT FROM AUTHOR]

Sub-orbital-scale climate variability of the last glacial period provides important insights into the rates at which the climate can change state, the mechanisms that drive such changes, and the leads, lags, and synchronicity occurring across different climate zones. Such short-term climate variability has previously been investigated using δ18O from speleothems (δ18O calc) that grew along the northern rim of the Alps (NALPS), enabling direct chronological comparisons with δ18O records from Greenland ice cores (δ18O ice). In this study, we present NALPS19, which includes a revision of the last glacial NALPS δ18O calc chronology over the interval 118.3 to 63.7 ka using 11, newly available, clean, precisely dated stalagmites from five caves. Using only the most reliable and precisely dated records, this period is now 90 % complete and is comprised of 16 stalagmites from seven caves. Where speleothems grew synchronously, the timing of major transitional events in δ18O calc between stadials and interstadials (and vice versa) are all in agreement on multi-decadal timescales. Ramp-fitting analysis further reveals that, except for one abrupt change, the timing of δ18O transitions occurred synchronously within centennial-scale dating uncertainties between the NALPS19 δ18O calc record and the Asian monsoon composite speleothem δ18O calc record. Due to the millennial-scale uncertainties in the ice core chronologies, a comprehensive comparison with the NALPS19 chronology is difficult. Generally, however, we find that the absolute timing of transitions in the Greenland Ice Core Chronology (GICC) 05 modelext and Antarctic Ice Core Chronology (AICC) 2012 are in agreement on centennial scales. The exception to this is during the interval of 100 to 115 ka, where transitions in the AICC2012 chronology occurred up to 3000 years later than in NALPS19. In such instances, the transitions in the revised AICC2012 chronology of Extier et al. (2018) are in agreement with NALPS19 on centennial scales, supporting the hypothesis that AICC2012 appears to be considerably too young between 100 and 115 ka. Using a ramp-fitting function to objectively identify the onset and the end of abrupt transitions, we show that δ18O shifts took place on multi-decadal to multi-centennial timescales in the North Atlantic-sourced regions (northern Alps and Greenland) as well as the Asian monsoon. Given the near-complete record of δ18O calc variability during the last glacial period in the northern Alps, we also offer preliminary considerations regarding the controls on mean δ18O calc for given stadials and interstadials. We find that, as expected, δ18O calc values became increasingly lighter with distance from the oceanic source regions, and increasingly lighter with increasing altitude. Exceptions were found for some high-elevation sites that locally display δ18O calc values that are heavier than expected in comparison to lower-elevation sites, possibly caused by a summer bias in the recorded signal of the high-elevation site, or a winter bias in the low-elevation site. Finally, we propose a new mechanism for the centennial-scale stadial-level depletions in δ18O such as the Greenland Stadial (GS)-16.2, GS-17.2, GS-21.2, and GS-23.2 "precursor" events, as well as the "within-interstadial" GS-24.2 cooling event. Our new high-precision chronology shows that each of these δ18O depletions occurred in the decades and centuries following rapid rises in sea level associated with increased ice-rafted debris and southward shifts of the Intertropical Convergence Zone, suggesting that influxes of meltwater from moderately sized ice sheets may have been responsible for the cold reversals causing the Atlantic Meridional Overturning Circulation to slow down similar to the Preboreal Oscillation and Older Dryas deglacial events. [ABSTRACT FROM AUTHOR]

Ice-nucleating particles (INPs) produce ice from supercooled water droplets through heterogeneous freezing in the atmosphere. INPs have often been collected at the Jungfraujoch research station (at 3500 m a.s.l.) in central Switzerland; yet spatially diverse data on INP occurrence in the Swiss Alps are scarce and remain uncharacterized. We address this scarcity through our Swiss alpine snow sample study which took place during the winter of 2018. We collected a total of 88 fallen snow samples across the Alps at 17 different locations and investigated the impact of altitude, terrain, time since last snowfall and depth upon freezing temperatures. The INP concentrations were measured using the home-built DRoplet Ice Nuclei Counter Zurich (DRINCZ) and were then compared to spatial, temporal and physicochemical parameters. Boxplots of the freezing temperatures showed large variability in INP occurrence, even for samples collected 10 m apart on a plain and 1 m apart in depth. Furthermore, undiluted samples had cumulative INP concentrations ranging between 1 and 200 INP mL -1 of snowmelt over a temperature range of -5 to -19 ∘ C. From this field-collected dataset, we parameterized the cumulative INP concentrations per cubic meter of air as a function of temperature with the following equation cair*(T)=e-0.7T-7.05 , comparing well with previously reported precipitation data presented in Petters and Wright (2015). When assuming (1) a snow precipitation origin of the INPs, (2) a cloud water content of 0.4 g m -3 and (3) a critical INP concentration for glaciation of 10 m -3 , the majority of the snow precipitated from clouds with glaciation temperatures between -5 and -20 ∘ C. Based on the observed variability in INP concentrations, we conclude that studies conducted at the high-altitude research station Jungfraujoch are representative for INP measurements in the Swiss Alps. Furthermore, the INP concentration estimates in precipitation allow us to extrapolate the concentrations to a frozen cloud fraction. Indeed, this approach for estimating the liquid water-to-ice ratio in mixed-phase clouds compares well with aircraft measurements, ground-based lidar and satellite retrievals of frozen cloud fractions. In all, the generated parameterization for INP concentrations in snowmelt could help estimate cloud glaciation temperatures. [ABSTRACT FROM AUTHOR]

The European Alps, the cradle of pioneering glacial studies, are one of the regions where geological markers of past glaciations are most abundant and well-studied. Such conditions make the region ideal for testing numerical glacier models based on simplified ice flow physics against field-based reconstructions and vice versa. Here, we use the Parallel Ice Sheet Model (PISM) to model the entire last glacial cycle (120-0 ka) in the Alps, using horizontal resolutions of 2 and 1 km. Climate forcing is derived using two sources: present-day climate data from WorldClim and the ERA-Interim reanalysis; time-dependent temperature offsets from multiple palaeo-climate proxies. Among the latter, only the European Project for Ice Coring in Antarctica (EPICA) ice core record yields glaciation during marine oxygen isotope stages 4 (69-62 ka) and 2 (34-18 ka). This is spatially and temporally consistent with the geological reconstructions, while the other records used result in excessive early glacial cycle ice cover and a late Last Glacial Maximum. Despite the low variability of this Antarcticbased climate forcing, our simulation depicts a highly dynamic ice sheet, showing that Alpine glaciers may have advanced many times over the foreland during the last glacial cycle. Ice flow patterns during peak glaciation are largely governed by subglacial topography but include occasional transfluences through the mountain passes. Modelled maximum ice surface is on average 861m higher than observed trimline elevations in the upper Rhône Valley, yet our simulation predicts little erosion at high elevation due to cold-based ice. Finally, despite the uniform climate forcing, differences in glacier catchment hypsometry produce a timetransgressive Last Glacial Maximum advance, with some glaciers reaching their modelled maximum extent as early as 27 ka and others as late as 21 ka. [ABSTRACT FROM AUTHOR]

A complex ice stream network occupied the European Alps during the last glacial maximum (LGM, MIS 2, Würmian Pleniglacial) with large valley glaciers extending as piedmont lobes into the northern and southern forelands. A completely different situation is reported for the easternmost Alps, where only a patchy pattern of isolated glaciers, confined to minor valleys, localized cirques and small plateaus could develop. Although the Alpine LGM glaciation was intensively studied, data sets vary considerably in the easternmost Alps (e.g concerning the numbers of local glaciers as well as extents) and systematic analyses of the glacial record are missing for the entire region. Consequently, equilibrium line altitudes (ELAs) and ELA depressions (ΔELAs) for these paleo glaciers remain unknown as well, though such data can be extremly useful to provide information on the variance of atmospheric circulation patterns over glacial to interglacial timescales. Characterized by relatively simple geometries and obviously rather simple source area relations (compared to the ice-stream network in the central Alps), they are most suitable for paleo-glacier reconstruction and ELA modelling – and can provide a robust dataset on ELA depression variabilities during the LGM. Such analysis is hardly possible for the ice-stream network occupying most of the central Alps at the same time.To fill this gap, we provide a new GIS-dataset of the LGM glaciation at the Eastern Alps based on the principal work of van Husen (1987), a number of case studies, geological maps, and the analyses of multiple orthophoto and DEM data. First systematic analyses on ELAs and ELA depressions of these low elevated isolated glaciers highlight the highly variable glacier response across the Eastern Alps to topographic and climatic forcing. [ABSTRACT FROM AUTHOR]

Speleothems from the northern rim of the European Alps (NALPS) have provided a number of important, high-resolution, precisely 230Th-dated records of both orbital and millennial-scale climate variability during the last glacial and interglacial periods. The isotopic signatures of such records have helped improve fundamental understanding of the effect that changes in atmospheric and North Atlantic circulation have on European climate, whilst the robust chronologies have provided important information about the timescales upon which the climate can change in this well-populated region. Furthermore, the pattern and timing of isotopic excursions in δ18O as recorded in the calcite of northern Alpine speleothems during the last glacial cycle has been shown to be synchronous within dating uncertainties with the sawtooth-pattern of changes in the δ18O of Greenland ice cores (known as Dansgaard-Oeschger cycles), thus reflecting the shared North Atlantic moisture source and integrated climate system. Here we present a revised chronology over the interval 120-60 ka. We have added an additional 5,000 δ18O measurements dated by 145 precise U-Th ages to the NALPS chronology of Boch et al. (2011), and subsequently taken the most reliable and precisely dated records for the final NALPS19 chronology. Within the interval 118.3 to 63.7 ka, the record is now 90 % complete, compared to 76 % in Boch et al. (2011). Where speleothems grew synchronously, major transitional events between stadials and interstadials (and vice versa) are all in agreement within uncertainty. The NALPS19 chronology is considered with respect to other Northern Hemisphere climate records. Furthermore, we consider the controls that operated on δ18O during the entire NALPS record over the interval c.120-20 ka. [ABSTRACT FROM AUTHOR]

Geomorphological evidence shows that during the last glacial period glaciers reached far intothe foreland of the Alps. How frequent such advances took place, how long the glaciersremained in advanced position and how fast they advanced or retreated, however, is difficultto reconstruct from geomorphology. Models of glacier flow are increasingly used to assess icedynamics during the last glacial period. Driving such models relies on a series ofestimates, including ice rheology, the forcing climate and glacier mass balance.Thereby, the latter strongly depends on climate and the equations used to describe theirconnection. Here, we focus on reconstructing surface melt of the Rhine glacier (∼16,000 km2) at thelast glacial maximum (LGM). Given large uncertainties in our knowledge of the LGMclimate, we base our estimates on (i) analogies from Arctic present-day climate and massbalance and on (ii) theoretical considerations. Thereby we investigate which are the keyclimatic characteristics that need to be specified to simulate LGM glacier melt. We find thatchanges in the amplitude of annual air temperature substantially influence simulatedablation-area mass balance gradients db∕dz, and thus glacier-wide mass balance. While thisinfluence has been shown in earlier research, it has not yet been considered in reconstructionsof glacier mass balance during the last glacial. Paleoclimatic evidence from Central Europe suggests that during the LGM annualamplitude of air temperature was larger than today. We show that computing LGM glaciermass balance while assuming no change in amplitude compared to present-dayclimate can result in an overestimation of db∕dz (∼0.4 m w.e. (100 m)−1 yr−1 vs.∼0.55 m w.e. (100 m)−1 yr−1). It remains to be explored how these differing db∕dz couldinfluence simulated glacier dynamics during the last glacial. [ABSTRACT FROM AUTHOR]

The last glacial period was punctuated by episodes of warm and humid climate. These rapid climate instabilities, called Dansgaard/Oeschger (D/O) events, lasted between a few hundred and a few thousand years. The triggering mechanism of these events is still not comprehensively decoded and various hypotheses are debated including oscillations of the Atlantic Meridional Overturning Circulation driven by changes in the freshwater budget, changes in the elevation of the Laurentide ice-sheet and its effect on wind stress and sea-ice cover, as well as ocean–sea ice interactions internal to the Nordic Seas. Morever, two time periods during the last glacial show a distinctive reduction or even an absence of D/Os (~70 to 60 ka and ~26 to 16 ka). Those periods concur with minimum sea-level and are important constraints to test hypotheses for the D/O triggering mechanism as not all of them can explain this absence of D/O cyclicity. Knowledge about D/O cyclicity could be improved by extending the investigations to the penultimate glacial. However, existing records cover only parts of the interval between ~200 and 130 ka or are located far from the D/O event core location and may have missed some events. Especially marine records, which would be ideally located in the North Atlantic to detect D/O events, are often limited with respect to their age control during this period. Here, we present a new, replicated and precisely dated speleothem record from the northern rim of the European Alps covering the penultimate glacial. This area has previously proven to be highly sensitive to rapid millennial-scale climate variations. Between ~202 and ~133 ka before present our new Alpine speleothem record reveals a similar number of D/O events as compared to the last glacial period. D/O events were notably absent during three ~8 ka-long intervals, which coincided with sea-level low-stands during the penultimate glacial. Hence, our results strongly support findings from the last glacial that D/O-events were precluded during intervals when the Northern Hemisphere ice sheets reached their maximum extent. [ABSTRACT FROM AUTHOR]

Latest insights from paleo-climatic research (Luetscher et al. 2015) and glacier modelling (Seguinot et al. 2018) suggest that ice build-up during the Last Glacial Maximum may not have been uniform across the European Alps. Favoured by predominant precipitation patterns and a steep topographic gradient, paleo-glaciers on the southern side of the Alps are believed to have reached their maximum extent earlier than glaciers that drained north. While reliable glacial chronologies based on radiocarbon and exposure dates are available for several of the major Italian amphitheatres, the LGM glaciation of the central part of the southern European Alps is a clear lack of knowledge. The latter's connection to the major Alpine ice domes makes understanding the Ticino/Toce glaciers behaviour especially critical. The present study aims on filling this gap of understanding with detailed mapping of the Toce/Ticino glacier combined with cosmogenic nuclide dating. A total of thirty rock samples for surface exposure dating has been collected from erratics deposited on the western shore of Lago Maggiore by the Ticino/Toce glacier. Preliminary Beryllium-10 results support an LGM extent larger than recently proposed (Bini et al. 2009). Next to LGM ages, the present data set together with field evidence also suggests a glacier re-advance following the LGM that ended with rapid down wasting of the glacier. ReferencesBini et al. 2009, Federal Office of Topography, Swisstopo.Luetscher et al. 2015, Nature Communications 7433. Seguinot et al. 2018, Cryosphere 12, 3265-3285. [ABSTRACT FROM AUTHOR]

Reconstruction of denudation rates through time is an important task to quantify andunderstand the impact of climate on landscape evolution. Cosmogenic nuclides have beenwidely used to infer denudation rates at the watershed scale from both present day sedimentsand past stratigraphic records. Here, we analyze the in situ 10Be cosmogenic concentrationin sediments of two long-piston cores that were collected offshore the Var River(Western Mediterranean Sea), precisely along the Var sedimentary ridge. Thesesedimentary archives have been well dated at a high resolution and analyzed forsediment provenance (Bonneau et al., 2017-EPSL) thus providing a unique record toreconstruct the denudation history of the Var catchment in the Southern French Alps overthe last 70 ka. This period covers the majority of the last glacial period and theassociated Dansgaard-Oeschger events, the last glacial maximum (LGM, 26-19 ka) andthe subsequent deglaciation (19-11 ka), and the Holocene, with all these eventsbeing precisely defined in the studied cores. Therefore, this setting offers the rareopportunity to study the impact of rapid climate fluctuations on denudation ratesin a mountainous glaciated catchment over a time scale that is not impacted bytectonics. We present 21 10Be paleo concentrations ranging from 1.24±0.51 x 104 atoms/gquartz to5.99±1.90 x 104 atoms/gquartz. The 10Be paleo concentrations overall are very similar topresent day 10Be concentrations (average of 4.20±0.67 x 104 atoms/gquartz at thewatershed’s outlet in 2016, or a denudation rate of 0.20 ±0.03 mm/year). This suggestssimilar paleo denudation rates between today, the 0-17 ka period and the 27-70 kaperiod. Only the LGM shows a clear change in 10Be concentrations with much lowerconcentrations (average of 1.68±0.48 x 104 atoms/gquartz) suggesting high denudation ratesduring this period of maximum glacial extent in the French Alps. These results suggest that climatic settings have a limited impact on overall denudationrates and that glaciers in the Mediterranean Alps either weren’t strong agents of erosionduring the MIS 3 (70-25 ka) or were smaller than previously thought. These results alsosuggest that only strong climatic fluctuations (such as the LGM) can induce meaningfulchanges in denudation rates. [ABSTRACT FROM AUTHOR]

Recent studies suggest that the eastern end of the Alps may have experienced almost one kilometer of surface uplift at post-Miocene times. In order to improve our understanding of the extent and magnitude of this not very well-constrained surface uplift event, we map planation surfaces in the Fischbach Alps of eastern Austria. In this region, elevations range from about 1800 m in the north to 350 m at the orogen-basin transition zone in the south. The Fischbach Alps remained ice-free during the glacial periods and thus offer the opportunity to interpret mapped planation surfaces in terms of pre-Pleistocene relict landscapes.Combining geomorphic mapping in the field and morphometric analysis, we identify several planation surfaces, which we correlate to established reference-surfaces in other parts of the Styrian block. In particular, we recognize planation surfaces at about 150 - 200 m (correlating with the Stadelberg/Zahrerberg-Level) and 25 - 80 m (correlating with the Niedere- and Mittlere Terassengruppe) above the current base-level of the Feistritz river. At higher elevations, we recognize relict landscapes that correlate with the Teichalm (Hubenhalt-Level). The results of our mapping extend our knowledge about surface uplift in the Plio-Pleistocene period further to the east and suggest that the Fischbach Alps experienced a southward tilting of the Styrian block during this time. Some peculiar changes in the drainage direction of the Feistritz along the (Anger-Piregg)-fault point towards tectonic unrest in the area during the Pliocene. [ABSTRACT FROM AUTHOR]

Last Glacial Maximum reconstructions of former glacier in the European Alps shows large ice expansion on the northern side of the Alps, with wide piedmont lobes spreading over lowlands (synthese in Ehlers et al., 2011). The general chronological outline of the LGM in the Alps suggests a fairly synchronous glacial maximum around 26-20 ka (marine isotope stage 2; Wirsig et al., 2016), in line with global data from the Northern Hemisphere. However, a long lasting debate persists in French Alps regarding the timing of the Late Pleistocene maximum ice lobe extent in the Lyon area, varying from MIS 2 to MIS 4 based on indirect and contradictory radiocarbon ages (Mandier et al., 2003) and field constraints (Monjuvent and Nicoud, 1988). This debate was further rekindled by recent alpine ice modelling studies (Becker et al., 2016; Seguinot et al., 2018).A clear and robust chronological constrain of the Lyon glacial lobe extent is now critical as it would have major implication in terms of our understanding of past atmospheric circulation patterns. Traditional dating techniques such as radiocarbon and cosmogenic nuclides exposure are challenging in this area due to the scarcity of organic material incorporated within glacial deposits and the huge scarcity of in-place moraine boulders. In these circumstances, Optically Stimulated Luminescence (OSL) techniques, which allow the dating of buried sedimentary material, offer a promising alternative. In this study, we propose a new chronological reconstruction of the Lyon Lobe maximum extent during the Late Pleistocene. This chronology is based on new OSL data measured from fluvio-glacial deposits located in presently dry valleys only active during the Late Pleistocene maximum extent of the Lyon Lobe. Our preliminary results suggest that in fact, two major phases of glacial advance of similar extent occurred during the Last Glacial cycle, around the MIS 2 and around the MIS 4. These results not only bring a fresh contribution to the debate of the local paleoglacial history in the French Western Alps but may also have significant implications in terms of Late Pleistocene glaciations pattern and paleoclimate evolution in the Alps. [ABSTRACT FROM AUTHOR]